1. Field of the Invention
The invention relates to powered surgical instruments. More particularly, the invention relates to temperature indicating elements for use with powered surgical instruments to provide a visual indication of the temperature of at least a portion of the surgical instrument. The invention also relates to thermal insulating devices for use with powered surgical instruments, these devices optionally including temperature indicating elements.
2. Description of the Prior Art
Powered surgical instruments are known for use during surgical procedures to operate a workpiece in some manner to perform the procedure. For example, a powered surgical instrument may be a handpiece, generally powered either electrically or pneumatically, in the form of a drill which rotates a drill bit or bur. Other handpiece instruments in the form of a saw operate a saw blade in either a reciprocating or oscillating manner. Various other types of powered surgical handpieces are known to move a tool or workpiece in various ways to perform surgical procedures.
In some powered surgical instruments the workpiece (e.g. burr or drill bit, etc.) is rapidly rotated to, for example, debride or resect soft tissue or bone. The workpiece is locked into a collet at the distal end of the instrument for fixed attachment to the motor drive shaft in the instrument. The workpiece generally extends distally from the collet in alignment with the axis of the drive shaft. In some instances a bur guard or similar bearing-containing device is interposed between the workpiece and the handpiece in order to provide additional rotary bearing support between the workpiece and the handpiece. In all instances, the rapid movement of the workpiece relative to the stationary components of the handpiece creates heat-generated friction which ultimately passes via thermal conduction or radiation from the internal friction-generating components to the external surface of the handpiece or bur guard (or other component). The invention is described in terms of powered surgical instruments because manually operated instruments would not be expected to generate a great deal of frictional heat. Clearly, if a manual instrument did generate sufficient heat to cause concern, the invention would be equally applicable to such instruments.
While powered surgical instruments are designed to be cleaned and sterilized after each use, it has been found that less than optimal cleaning and/or sterilization by users contributes to greater than normal generation of friction upon subsequent use and, consequently, greater than normal temperature rise in the components of the instrument and/or workpiece. In some instances, the heat generated by a powered surgical instrument may be so great as to make it unable to be held by a surgeon or may be so great as to cause injury to a patient. In particular, use of such potentially very hot instruments in small areas, such as during oral surgical procedures, raises the possibility that a patient will be burned inadvertently. It would, therefore, be desirable to provide some indication that a part of the surgical instrument is beginning to get hotter than intended. It would also be desirable to provide a way to protect the patient from sudden temperature increases of surfaces of powered surgical instruments likely to come in contact with the patient.
It is accordingly an object of this invention to produce a temperature indicating device to provide an indication of the temperature of at least a portion of a powered surgical instrument.
It is another object of this invention to provide a temperature indicating device for attachment to a specific portion of a powered surgical instrument to provide a visual indication of the temperature of that portion.
It is also an object of this invention to provide a temperature indicating device for attachment at the distal end of a powered surgical instrument adjacent to the collet through which the workpiece passes.
It is yet another object of this invention to provide a temperature indicating device capable of attachment to the distal end of an instrument at a location most clearly visible by a user.
It is an additional object of this invention to produce a method for indicating a predetermined temperature of a portion of a surgical instrument.
It is still another object of this invention to provide a thermal insulator device to be interposed between a patient and a potentially high temperature portion of a powered surgical instrument being used on the patient.
It is also an object of this invention to provide such a thermal insulating device with a temperature indicating element to provide a visual indication of the temperature of the portion of the powered surgical instrument to which it is attached.
These and other objects of the invention are achieved by the preferred embodiment disclosed herein which is a thermochromic indicating device for providing a visual signal indicative of a temperature change of at least a portion of a powered surgical instrument. The instrument has a proximal end and a distal end, the distal end being generally cylindrical and adapted to have an elongated workpiece extending distally therefrom. The indicating device is a generally cylindrical shell having an open proximal end and a closed, apertured distal end, a cylindrical wall with an axis and a predetermined axial length. The end wall enclosing the distal end has a workpiece-receiving aperture. The cylindrical wall is adapted to be received in contiguous engagement on the distal end of the instrument with the workpiece extending through said workpiece-receiving aperture. A temperature sensitive dye is embedded in the cylindrical shell to sense the temperature of the distal end of the instrument which is in contiguous engagement with the cylindrical shell. The dye changes color at a predetermined temperature to provide a visual indication of a change in the temperature of the device.
Another aspect of the invention is a device such as that described above, but without any thermochromic elements therein. Such a device would have insulating properties alone.
Another aspect of the invention is a thermochromic element embodied in the form of a paint having thermochromic elements therein. Such an embodiment would not necessarily have the insulating properties of the previous embodiments.
Another aspect of the invention is the method of operating a powered surgical instrument with the insulating and/or thermochromic elements described above. These methods comprise the steps of affixing the insulating and/or thermochromic elements to a selected portion of a powered surgical instrument as it is being used on a patient.